Alert archive / Indiana / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 64, NWS Chicago, IL

June 27, 2020Iroquois County, Illinois; Benton County, Newton County, Indiana

NWS Chicago, IL issued this severe thunderstorm warning at Jun 27, 2020, 3:44 AM CDT for Iroquois County, Illinois; Benton County, Newton County, Indiana. It was in force for 28 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jun 27, 2020, 3:44 AM CDT (08:44 UTC)
Expired: Jun 27, 2020, 4:12 AM CDT
In force: 28 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

Counties Iroquois County, IL, Benton County, IN, Newton County, IN

The radar

The Chicago radar (KLOT), 105 km from the middle of the area, began a volume at 08:46 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 8.7 hours before the alert went out and 115 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1233 J/kg
Mixed-layer CIN: -42 J/kg
Mixed-layer LCL: 1733 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 61 m²/s²
0-3 km storm-relative helicity: 185 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.6

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Chicago, IL wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 27, 3:31 AM CDT, 13 minutes earlier.

Area forecast discussion, Jun 27, 3:31 AM CDT, 13 minutes before

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Hazardous weather outlook, Jun 26, 3:43 PM CDT, 12 hours 1 minute before

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
343 PM CDT Fri Jun 26 2020

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-272045-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
343 PM CDT Fri Jun 26 2020 /443 PM EDT Fri Jun 26 2020/

This Hazardous Weather Outlook is for portions of North Central
Illinois...Northeast Illinois and Northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Significant Thunderstorm Risk...with an associated:
     Significant damaging wind risk...up to 70 mph.
     Elevated hail risk...up to the size of quarters.
     Elevated Tornado risk.
  Limited Flooding Risk...mainly along and north of I-80.

DISCUSSION...

Scattered thunderstorms will gradually increase in coverage
through early evening peaking throughout the evening hours and
then gradually working southward and fading into the overnight.
Damaging wind gusts will be the main threat, but a risk for a
few brief tornadoes exists as well. A threat for flash flooding
also is present, mainly north of I-80. Thunderstorms will slowly
sink southeastward into the overnight with likely a weakening
trend.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Saturday...
  Limited Severe Thunderstorm Risk.
  Limited Flooding Risk.
Sunday...
  Limited Thunderstorm Risk.
  Limited Excessive Heat Risk.
Monday and Tuesday...
  Limited Thunderstorm Risk.
  Limited Excessive Heat Risk.
Wednesday and Thursday...
  Limited Thunderstorm Risk.

DISCUSSION:

Scattered thunderstorms are possible on Saturday with the greatest
coverage along and south of I-80. Some of these may produce
locally heavy rainfall and gusty downburst winds. A continued
chance for storms will persist into Sunday.

Another round of thunderstorms may develop very late Sunday night
into Monday morning. Thereafter, a daily chance for mainly
isolated to widely scattered thunderstorms exists through
Thursday.

Heat index values will likely to rise above 95 on Monday and
Tuesday away from the lake.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation is requested through mid evening.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the east at 40 to 45 mph.

LMZ740>745-272045-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
343 PM CDT Fri Jun 26 2020

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

Weather hazards expected...

  Hazardous conditions for small craft.
  Significant Thunderstorm Risk...with an associated:
     Significant Thunderstorm Wind Gust Risk...up to 60 knots.
     Elevated Hail Risk...up to the size of quarters.
     Elevated Waterspout Risk.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Saturday through Thursday...
  Limited Thunderstorm Risk.

MTF

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In the hours before

Local storm report, Jun 27, 12:20 AM CDT, 3 hours 24 minutes before

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Special weather statement, Jun 27, 12:52 AM CDT, 2 hours 52 minutes before

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Special weather statement, Jun 27, 1:24 AM CDT, 2 hours 20 minutes before

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Special weather statement, Jun 27, 1:40 AM CDT, 2 hours 4 minutes before

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Special weather statement, Jun 27, 3:02 AM CDT, 42 minutes before

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Special weather statement, Jun 27, 3:41 AM CDT, 3 minutes before

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The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 26, 7:01 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane, Kendall	44 min
Jun 26, 7:07 PM CDT	Special Marine Warning	LOT		53 min
Jun 26, 7:12 PM CDT	Flash Flood Warning	LOT	Cook, DuPage, Kane	3 hr
Jun 26, 7:26 PM CDT	Special Weather Statement	LOT	DuPage	19 min
Jun 26, 7:41 PM CDT	Special Weather Statement	LOT	Kendall	34 min
Jun 26, 7:49 PM CDT	Special Weather Statement	LOT	Cook	26 min
Jun 26, 7:51 PM CDT	Special Weather Statement	LOT	Will	24 min
Jun 26, 7:52 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kane, Kendall, Will	3 hr
Jun 26, 7:53 PM CDT	Special Marine Warning	LOT		37 min
Jun 26, 7:53 PM CDT	Special Weather Statement	LOT	LaSalle	22 min
Jun 26, 8:04 PM CDT	Special Weather Statement	LOT	Grundy, Will	56 min
Jun 26, 8:22 PM CDT	Severe Thunderstorm Warning	LOT	Cook, Grundy, Kankakee, LaSalle, Livingston, Will	53 min
Jun 26, 8:53 PM CDT	Severe Thunderstorm Warning	LOT	LaSalle, Livingston	40 min
Jun 26, 10:37 PM CDT	Areal Flood Advisory	LOT	Grundy, Iroquois, Kankakee, LaSalle, Livingston, Will	3 hr
Jun 26, 10:51 PM CDT	Special Weather Statement	LOT	Kankakee	39 min
Jun 27, 12:52 AM CDT	Special Weather Statement	LOT	Iroquois	38 min
Jun 27, 3:02 AM CDT	Special Weather Statement	LOT	Iroquois	28 min
Jun 27, 3:41 AM CDT	Special Weather Statement	LOT	Iroquois	34 min
Jun 27, 4:50 AM CDT	Special Weather Statement	LOT	Ford, Iroquois	55 min
Jun 27, 5:37 AM CDT	Areal Flood Advisory	LOT	Iroquois	3 hr
Jun 27, 5:44 AM CDT	Special Weather Statement	LOT	Ford	46 min
Jun 27, 3:32 PM CDT	Flash Flood Warning	LOT	Iroquois	4 hr
Jun 27, 3:50 PM CDT	Special Weather Statement	LOT	LaSalle	25 min
Jun 27, 4:12 PM CDT	Special Weather Statement	LOT	Iroquois	33 min
Jun 27, 4:16 PM CDT	Special Weather Statement	LOT	LaSalle	29 min
Jun 27, 4:29 PM CDT	Flash Flood Warning	LOT	Ford, Iroquois, Kankakee	3 hr
Jun 27, 4:34 PM CDT	Severe Thunderstorm Warning	LOT	Iroquois	41 min
Jun 27, 4:45 PM CDT	Special Weather Statement	LOT	Kankakee	30 min
Jun 27, 5:58 PM CDT	Special Weather Statement	LOT	Kankakee	32 min
Jun 27, 6:10 PM CDT	Areal Flood Advisory	LOT	Iroquois	2 hr
Jun 27, 6:48 PM CDT	Special Weather Statement	LOT	Kankakee	27 min
Jun 26, 8:50 PM CDT	Severe Thunderstorm Warning	LOT	Jasper, Lake, Porter	25 min
Jun 26, 10:14 PM CDT	Special Weather Statement	LOT	Jasper, Newton	31 min
Jun 26, 11:17 PM CDT	Special Weather Statement	LOT	Jasper	43 min
Jun 26, 11:46 PM CDT	Special Weather Statement	LOT	Benton	59 min
Jun 27, 12:04 AM CDT	Severe Thunderstorm Warning	LOT	Benton, Jasper, Newton	41 min
Jun 27, 1:24 AM CDT	Special Weather Statement	LOT	Benton	36 min
Jun 27, 1:40 AM CDT	Special Weather Statement	LOT	Porter	35 min
Jun 27, 1:53 PM CDT	Areal Flood Advisory	LOT	Benton, Jasper, Newton	112 min
Jun 27, 2:22 PM CDT	Special Weather Statement	LOT	Benton	38 min

Nearby

Severe Thunderstorm Warnings in Indiana, 2020 Severe Thunderstorm Warnings in Illinois, 2020 Every severe thunderstorm warning in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.